In music, harmony is the use of simultaneous pitches (tones, notes), or chords.[1] The study of harmony involves chords and their construction and chord progressions and the principles of connection that govern them.[2] Harmony is often said to refer to the "vertical" aspect of music, as distinguished from melodic line, or the "horizontal" aspect.[3]Counterpoint, which refers to the interweaving of melodic lines, and polyphony, which refers to the relationship of separate independent voices, are thus sometimes distinguished from harmony.

Definitions, origin of term, and history of use

The term harmony derives from the Greekἁρμονία (harmonía), meaning "joint, agreement, concord",[4] from the verb ἁρμόζω (harmozo), "to fit together, to join".[5] The term was often used for the whole field of music, while "music" referred to the arts in general.

In Ancient Greece, the term defined the combination of contrasted elements: a higher and lower note.[6] Nevertheless, it is unclear whether the simultaneous sounding of notes was part of ancient Greek musical practice; "harmonía" may have merely provided a system of classification of the relationships between different pitches. In the Middle Ages the term was used to describe two pitches sounding in combination, and in the Renaissance the concept was expanded to denote three pitches sounding together.[6]